This spring has been quite a season for hacking. Sony, the International Monetary Fund, CitiGroup and Lockheed Martin all seem to have fallen victim to malicious security breaches. The cyber break-ins have caused financial havoc, personal inconvenience -- Sony's breach famously shut down its online gaming service and potentially compromised the personal information of millions of users -- and, in the case of IMF, might have affected countries' national economic security. Now, some computer scientists and engineers say they're developing a way to protect a potential future target of cyber attacks: implantable medical devices.